Flexible wiring member, liquid droplet jetting head, and method for connecting flexible wiring member and device

ABSTRACT

A flexible wiring member which connects a device and an external signal source has a plurality of wire members in which a plurality of wires are formed on one surface of a substrate, and a plurality of wire members is stacked to face the device. A plurality of bumps for connecting with the device are provided to the wires on a surface, of the wirings, facing the device. Bumps of one of the wire members overlapping with the other of the wire members face the device via the through hole formed in the other of the wire members. Accordingly, it is possible to realize high densification of wires in the flexible wiring while suppressing a rise in a cost.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationNo. 2007-161119, filed on Jun. 19, 2007, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a flexible wiring member which connectsa device and an external signal source, a liquid droplet jettingapparatus in which the flexible wiring member is used, and a method ofconnecting the flexible wiring member and the device.

2. Description of the Related Art

In a liquid droplet jetting apparatus which jets liquid droplets fromnozzles, a driving signal is input to an actuator having drive portionseach corresponding to one of the nozzles, via a flexible wire.Accordingly, the drive signal selectively applies a jetting pressure toa liquid.

In the liquid droplet jetting apparatus, when the number of nozzles isincreased and the nozzles are arranged highly densely, the driveportions are also arranged highly densely. Therefore, it is necessary tomake fine a wiring pattern of the flexible wire to be connected to thedrive portion, and to increase the number of wires in the flexible wire.Here, for avoiding an increase in a size of a flexible wiring member, itis necessary to make the wiring pattern highly dense. However, when awidth of each wire becomes thin by making the wiring highly dense, anelectrical resistance of each wire becomes high. Moreover, amanufacturing cost of the flexible wire rises up. Therefore, there havebeen limitations in making the wiring pattern fine.

For facilitating high densification of the wires in the wiring pattern,in Japanese Patent Application Laid-open No. 2004-303885 (FIGS. 1 3), afirst wire layer is provided on a front surface of the flexible wire,and a second wire layer is provided on a rear surface of the flexiblewire. Moreover, the second wire layer on the rear surface is exposed toa surface via an opening of a through hole in the flexible wire.Further, an element to be connected to the flexible wire is arranged ona front surface side. The element has two types of electrode portions ofdifferent heights. An electrode portion on a lower side is connected tothe first wire layer and the other electrode portion on a higher side isconnected to the second wire layer via the opening.

SUMMARY OF THE INVENTION

However, the flexible wiring member described in Japanese PatentApplication Laid-open No. 2004-303885 has a wiring pattern formed on itsboth surfaces. Such a flexible wire of a double-sided wiring type has ahigh cost as compared to a single-sided wiring type in which the wiringis made on only one surface.

The present invention has been made to solve the abovementionedproblems, and an object of the present invention is to realize a highdensification of wires in a flexible wiring member while suppressing arise in the cost.

According to a first aspect of the present invention, there is provideda flexible wiring member which is arranged to face a device, and whichconnects the device and an external signal source, including:

two wire members which are stacked mutually, and each of which have abelt-shaped substrate, a plurality of wires formed on one surface of thesubstrate, a plurality of electrodes connected to the wiresrespectively, and a plurality of bumps each projected from one of theelectrodes toward the device,

wherein a plurality of through holes is formed in one of the wiremembers stacked on a side of the device, and the bumps of the other ofthe wire members face the device through the through holes formed in theone of the wire members.

According to the first aspect of the present invention, the plurality ofwire members are stacked, and bumps in the form of a protrusion forconnecting with the device is provided to each of the(electroconductive) wires on a surface on a side of the device(electrical load) in each of the wire members. Moreover, the structureis such that one of the wire members is arranged on the other of thewire member which is arranged to face the device, and the bumps of theone of the wire members overlap with the device via the through holeformed in the other wire member. In other words, since the bumps to beconnected to the device is formed to be distributed (divided) in theplurality of wire members, it is possible to decrease the number ofbumps to be formed in each of the wire members. In other words, since itis possible to decrease the number of electroconductive wires to bewired in each of the wire members, it is possible to decrease a wiredensity in spite of the number of electroconductive wires necessary fordriving the device. Therefore, it is also possible to increase a widthof each of the wires. Consequently, even when the drive portions areprovided densely to the device, since it is possible to decrease a wiredensity (density of wires) of each of the wire members by using wiremembers each having wirings only on a single side (single-sided wiring),it is possible to facilitate a reduction in a cost of components of thewire members.

Moreover, since the wire members are stacked to overlap with each other,it is possible to make small (reduce) an area in a plan view of theflexible wiring member as compared with the case in which the wiremembers are arranged side by side, and it also shows an effect of savingthe space.

In the flexible wiring member of the present invention, the bumps of theother of the wire members facing the device via the one of the wiremembers may be formed to be projected, from a facing surface of theother of the wire members facing the device through the through holesformed in the one of the wire members; and height of the bumps of eachof the two wire members may be adjusted such that a projection amount ofa portion of the bumps projected through the through holes projectingfrom the facing surface is same as a projection amount, of a portion ofthe bumps provided on the one of the wire members projecting from thefacing surface.

In this case, the height of the bumps is adjusted for each of the wiremembers such that the amount of protrusion of the bumps protruded, fromthe surface facing the device, via the through holes and the amount ofprotrusion of the bumps provided on one of the wire members nearest tothe device, from the surface facing the device, become substantially thesame. In other words, since a front end on a side of the device (towardthe device) of all the bumps is formed to be in the same plane, it ispossible to prevent a faulty connection (connection defect) at the timeof connecting the bumps of the stacked wire members, to the device.

In the flexible wiring member of the present invention, the bumpsprovided on the two wire members respectively may be arranged to bedistributed mutually.

In this case, the bumps provided to each of the wire members arearranged to be distributed (divided) mutually in a plan view from adirection of stacking. Therefore, even when the electroconductive wiresfor each of the wire members are arranged to be mixed in a plan view,and a wire pitch of each of the wire members can be rough, and it ispossible to make dense a wiring pitch as a whole.

In the flexible wiring member of the present invention, the two wiremembers may be drawn in a same direction from the device; a circuitelement may be mounted on an area, of each of the wire members, in whichthe wire members are drawn; and a signal from the external signal sourcemay be inputted to the device via the circuit element.

In this case, since the wire members are drawn in the same directionfrom the device, the circuit element mounted in the area drawn of eachof the wire member is positioned in the same direction with respect tothe device. Therefore, it is possible to arrange a heat releasing body(heat sink) which is to be brought in contact with the circuit elementfor releasing heat of the circuit element at one place (location), or itis possible to arrange integrally such that the heat releasing bodymakes a contact with all the wire elements, thereby facilitating thesaving of space.

In the flexible wiring member of the present invention, the one surfaceof the substrate, of each of the wire members, may be insulative, thewires and a covering material having an insulating property may bestacked on the one surface of the substrate; and each of the bumps maybe formed at a portion of the substrate, at which a part of thesubstrate is removed such that one of the wires is exposed to the othersurface of the substrate, or each of the bumps may be formed at anotherportion of the substrate, at which a part of the covering material isremoved such that the wire is exposed to the one surface of thesubstrate.

In this case, the bumps may be formed at the sites at which theelectroconductive wires are exposed to the other surface of thesubstrate, by partially removing the substrate. Alternately, the bumpsmay be formed at the sites at which the electroconductive wires areexposed to the one surface of the substrate, by partially removing thecovering material. In other words, the bumps can be formed on a surface,of the one of the wire members, facing the device and being covered withthe substrate, or the bumps can be formed on a surface, of the one ofthe wire members, facing the device and being covered with the coveringmaterial. In this way, it is possible to change the surface, of one ofthe wire members, on which the bumps are to be formed depending on thecases.

According to a second aspect of the present invention, there is provideda liquid droplet jetting head which jets droplets of different types ofliquids, including:

a flexible wiring member which is arranged to face a device, and whichconnects the device and an external signal source, the flexible wiringmember including two wire members which are stacked mutually and each ofwhich has a belt-shaped substrate, a plurality of wires formed on onesurface of the substrate, a plurality of electrodes connected to thewires respectively, a circuit element arranged on the substrate, and aplurality of bumps which are projected from the electrodes toward thedevice, one of the wire members stacked on a side of the device having aplurality of through holes formed in one of the wire members, and eachof the bumps of the other of the wire members facing the device via oneof the through holes formed in the one of the wire members;

a cavity section which is filled with the liquid, and in which aplurality of nozzle groups corresponding to the types of the liquidsrespectively are formed, each of the nozzle groups having a plurality ofnozzles; and

an actuator serving as the device and including a plurality of drivingsections which correspond to the nozzles respectively and which applyselectively a jetting pressure to the liquids, respectively, in thecavity section,

wherein the circuit element is mounted on each of the wire members ofthe flexible wiring member, and a signal from the external signal sourceis divided into a plurality of driving signals each traveling one of thewire members and each of the driving signals is inputted to the drivingsections via one of the circuit elements; and

a part of the driving signals traveled through the circuit element ofeach of the two wire members is distributed and inputted to a part, ofthe driving sections, corresponding to the nozzles in different nozzlegroups.

According to the second aspect of the present invention, an arrangementis made such that a plurality of driving signals via the same circuitelement are inputted upon being distributed (divided in) to the drivingsections corresponding to the nozzles in different nozzle groups. Inother words, not only one circuit element but a plurality of circuitelements correspond to one of the nozzle groups. Since each of thecircuit elements has a slight variation in characteristics, when onecircuit element is connected such that the circuit element correspondsto a certain nozzle group, there occurs to be a variation incharacteristics of the nozzle groups due to the variation incharacteristics of the circuit elements. Therefore, it is possible tosuppress the variation in characteristics among the nozzle groups bymaking the arrangement as described above, and distributing thevariation in the circuit elements to all the nozzle groups.

According to a third aspect of the present invention, there is provideda flexible wiring member which is connectable to a device having aplurality of bumps of different heights, including:

two wire members which are stacked mutually and each of which has abelt-shaped substrate, a plurality of wires formed on one surface of thesubstrate; and

a plurality of electrodes connected to the wires respectively,

wherein a plurality of through holes is formed in one of the wiremembers stacked on a side of the device, and each of the electrodes ofthe other of the wire members is exposed to the device, via the one ofthe through holes formed in the one of the wire members.

According to the third aspect of the present invention, since theelectrodes to be connected to the device are formed to be distributed tothe plurality of wire members, it is possible to decrease the number ofelectrodes to be formed in each of the wire members. In other words,since it is possible to decrease the number of electroconductive wiresto be wired in each of the wire members, with respect to the number ofelectroconductive wires required for driving the device, it is possibleto decrease a wire density, and to make thick a wiring pitch.Consequently, even when the driving sections are provided densely to thedevice, it is possible to use a wire member having a single-sidedwiring, and to decrease the wire density (wiring density) of each of thewire members. Therefore, it is possible to facilitate the reduction inthe cost of components of the wire members.

The device to be connected to the flexible wiring of the third aspect ofthe present invention may have a plurality of first bumps which isconnectable to the electrodes of the one of the wire members; and aplurality of second bumps which is connectable to the electrodes of theother of the wire members and having a height greater than that of thefirst bumps, wherein a difference in the height of the first bumps andthe height of the second bumps may be equivalent to a thickness of theone of the wire members. In this case, since a front end toward theflexible wiring of the first bump and the second bump are formed to bein the same plane, it is possible to prevent a faulty connection(connection defect) at the time of connecting the bump of the wiremembers stacked, to the device.

According to a fourth aspect of the present invention, there is provideda method for connecting a flexible wiring member and a device,including:

preparing a first flexible wiring member and a second flexible wiringmember, each of which has a belt-shaped substrate and a plurality ofwires formed on one surface of the substrate;

forming a plurality of electrodes on the wires of each of the firstflexible wiring member and the second flexible wiring member;

forming a plurality of through holes in the first flexible wiringmember;

positioning and stacking the first flexible wiring and the secondflexible wiring with each other such that areas, of the first flexiblewiring, in which the through holes are formed face areas, of the secondflexible wiring member, at which the electrodes are to be formed;

forming bumps on the electrodes of each of the first flexible wiring andthe second flexible wiring;

exposing the bumps of the second flexible wire via the through holes;and

connecting the bumps, formed on the first flexible wiring and the secondflexible wiring, to the device.

According to the fourth aspect of the present invention, since the bumpsto be connected to the device are formed to be distributed to theplurality of flexible wire members; it is possible to decrease thenumber of bumps to be formed in each of the wire members. In otherwords, since it is possible to decrease the number of electroconductivewires to be wired in each of the wire members, with respect to thenumber of electroconductive wires required for driving the device, it ispossible to decrease a wire density, and to make thick a wiring pitch.Moreover, the through holes are formed in one of the wire members, andpositioning is carried out such that the through holes and theelectrodes of the other wire member are facing mutually. Therefore, itis possible to expose the electrodes of the other wire member throughthe through holes. Therefore, it possible to expose, from the same sideof the wire members, the bumps formed on the electrodes of the twoflexible wire members, and wiring with the device becomes easy.

In the method of the present invention, the one surface of the substrateof each of the first flexible wiring member and the second flexiblewiring member may have an insulating property; and each of the firstflexible wiring member and the second flexible wiring member may have acovering material having an insulating property, and the wires and thecovering material may be stacked on the one surface of the substrate ofeach of the first flexible wiring member and the second flexible wiringmember; and the electrodes may be formed to be exposed on the othersurface of the substrate by removing a part of the substrate, or to beexposed on the one surface of the substrate by removing a part of thecovering material. In this case, in each of the cases namely a case inwhich the surface facing the device is the one surface of the substrate,and a case in which the surface facing the device is the other surfaceof the substrate, it is possible to change the surface on which thebumps are to be formed according to the case.

In the method of the present invention, after the first flexible wiringmember and the second flexible wiring member may be positioned andstacked with each other, the through holes are formed in the firstflexible wiring member, and the electrodes of the second flexible wiringmember are formed. In this case, it is possible to expose the electrodeof the second flexible wiring from the through hole by removing a partof the covering material or the substrate of the second flexible wiringsimultaneously with forming the through hole in the first flexiblewiring. Therefore, it is possible to simplify the process, andconnections of the wires become easy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a recording apparatus to which, aliquid droplet jetting head of the present invention is applied;

FIG. 2 is an exploded perspective view of a carriage;

FIG. 3 is a vertical cross-sectional view in which, a head holder in afirst embodiment is cut along a Y direction;

FIG. 4 is a vertical cross-sectional view in which a jetting head is cutalong the Y direction;

FIG. 5 is a plan view of an actuator;

FIG. 6A is a vertical cross-sectional view before a first wire memberand a second wire member in the first embodiment are overlapped, andFIG. 6B is a vertical cross-sectional view of the first wire member andthe second wire member in an overlapped state;

FIG. 7A is a schematic bottom view of the second wire member, FIG. 7B isa schematic bottom view of the first wire member, and FIG. 7C is aschematic bottom view of the first wire member and the second wiremember in an overlapped state;

FIG. 8 is a schematic bottom view of a nozzle surface;

FIG. 9 is a vertical cross-sectional view in which, a head holder in asecond embodiment is cut in the Y direction;

FIG. 10A is a vertical cross-sectional view before a first wire memberand a second wire member in the second embodiment are overlapped, andFIG. 10B is a vertical cross-sectional view of the first wire member andthe second wire member in an overlapped state;

FIG. 11 is a diagram showing an example in which bumps of differentheights are formed on (in) the actuator;

FIG. 12 is a flowchart showing a method of connecting the flexiblewiring and the device according to the present invention; and

FIG. 13A to FIG. 13G are diagrams showing a process from steps S1 to S7in FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention will be described below withreference to the accompanying diagrams. FIG. 1 is a schematic plan viewof an ink-jet printer (recording apparatus) 1 according to (as anembodiment of) a liquid jetting apparatus of the present invention. Theink-jet printer 1 jets an ink from nozzles. The ink-jet printer 1 may beapplied to an independent printer apparatus. Or the ink-jet printer 1may be applied to a printer mechanism (recording section) of amulti-function apparatus which is provided with a plurality of functionssuch as a facsimile function and a copy function. In the followingdescription, a direction of jetting of the ink from the nozzles to amedium is defined as a downward direction and a direction opposite tothe downward direction is defined as an upward direction.

As shown in FIG. 1, the recording apparatus (ink-jet printer) 1 includesa carriage 2. A jetting head (liquid jetting apparatus) 3 is mounted onthe carriage 2. Nozzles 7 are formed in the jetting head 3 (refer toFIG. 4), and the nozzles 7 are exposed on a lower surface of thecarriage 2. The carriage 2 is supported, on a first guide member 5 and asecond guide member 6, movably in a main scanning direction (Y-axisdirection). The carriage 2 reciprocates along the Y-axis direction by atiming belt 11 which is put around a driven pulley 10 and a drive pulley9 coupled with (linked to) a carriage motor 8. A paper on which the inkis jetted is transported in a secondary scanning direction (X-axisdirection) which is orthogonal to the main scanning direction (Y-axisdirection), at a lower side of the carriage 2.

An ink cartridge 13 which is replaceable is arranged inside an apparatusbody 12. Here, in accordance with the number of ink colors, four inkcartridges 13 for a black ink, a cyan ink, a magenta ink, and a yellowink respectively, are provided. The ink in each ink cartridge 13 issupplied independently to the carriage 2 via a supply tube. An inksupply tube 15 made of a resin material having flexibility, is used asthe supply tube.

As shown in FIG. 2, the carriage 2 includes a head holder 20 which issubstantially box-shaped, having an opening on an upper surface. Areinforcing frame 24 is arranged on a lower surface side of a bottomplate 21 of the head holder 20, and further, the jetting head 3 is fixedto the reinforcing frame 24. In other words, the jetting head 3 isarranged on the bottom plate 21 of the head holder 20 via thereinforcing frame 24. A front frame 28 is stuck on a lower surface sideof the reinforcing frame 24, such that the front frame 28 surrounds thejetting head 3 for modifying a step (unevenness) at a lower surface sideof the head holder 20 (refer to FIG. 3).

An ink storage portion 22 which temporarily stores the ink which issupplied from the ink cartridge 13, and a circuit board 23 are mountedon an upper surface side of the bottom plate 21 of the head holder 20.The circuit board 23 receives a driving signal from a control unit (anexternal signal source) which is installed in the apparatus main body12, via a flexible wire cable, and supplies a driving signal to anactuator 32 of the jetting head 3, via a flexible wiring 4.

In the first embodiment, the actuator 32 is connected to the circuitboard 23 by the flexible wire member 4 and a flexible auxiliary wire 51both of which are connected in an extension direction thereof. Theflexible wiring 4 is connected to the actuator 32, and the auxiliarywire 51 is connected to a connector 23 a of the circuit board 23 onwhich the circuit element 50 is mounted. Moreover, the flexible wiring 4has a stacked structure in which two strip-shaped wire members, 41 and42 (a first wire member 41 and a second wire member 42) overlapvertically (up and down). Each of the first wire member 41 and thesecond wire member 42 includes the circuit element 50, and is connectedto the circuit board 23 via the auxiliary wire 51. A stacked structureof the first wire member 41 and the second wire member 42 will bedescribed later.

For the flexible wiring 4 (the first wire member 41 and the second wiremember 42), a chip on film (COF), in which it is possible to design awiring pattern freely and on which the circuit element 50 is mounted, isused. For the auxiliary wire 51, a cable such as a general purposeflexible flat cable (FFC) and a flexible printed cable (FPC) in whichconductive wires are wired in parallel is suitable. It is possible toreduce an amount of a high cost chip on film (COF) by using such generalpurpose auxiliary wire 51, and to reduce a component cost. As a matterof course, the auxiliary wire 51 may have a plurality of general purposewire members connected mutually. Or the auxiliary wire member 51 may notbe the general purpose wire member but a chip on film (COF).

A through hole is formed in the bottom plate 21 of the head holder 20,and at an inner side of an opening 21 a of the through hole, an inkoutflow port 22 a of the ink storage portion 22, and an ink intake(inflow) port 31 a of the jetting head 3 are connected via a connectinghole 24 a of the reinforcing frame 24. Accordingly, ink is suppliedindependently for each color, from the ink storage portion 22 to thejetting head 3.

A slit hole 25, through which the flexible wiring 4 is passed is formedin the bottom plate 21, at a position toward one side wall 20 a of thehead holder 20. Moreover, a plurality of through holes 27 is formed inthe bottom plate 21, along the two mutually facing side walls 20 a. Thethrough holes 27 are used for pouring an adhesive 26 for fixing thejetting head 3 on the lower surface side of the bottom plate 21.Moreover, two pins 21 b for positioning and fixing a heat releasing body(heat sink, radiator plate) 52 are arranged on the bottom plate 21.

The circuit element 50 mounted on the flexible wiring 4 outputs adriving signal at a high frequency at the time of recording by therecording apparatus by jetting the ink from the nozzles. Therefore, thecircuit element 50 generates heat along with outputting the drivingsignal. For releasing the heat, a heat releasing body 52 of a metallicmaterial such as aluminum is provided in a close contact with thecircuit element 50, at the inner side of the head holder 20. The circuitelement 50 is mounted on each of the wire members 41 and 42. The heatreleasing body 52 has an upper plate portion 52 a and a lower plateportion 52 b, and the upper plate portion 52 a and the lower plateportion 52 b are coupled in U-shape (refer to FIG. 2). Therefore, it ispossible to make a contact with both the circuit elements 50. A pressing(pushing) member 54 is arranged on an upper side of the heat releasingbody 52. Two holes 52 c are formed in the heat releasing body 52 and twoholes 54 a are formed in the pressing member 54, each of the holes 52 c,54 a being engaged with one of the pins 21 b.

An upper surface of the upper plate portion 52 a of the heat releasingbody 52 is in a close contact with a lower surface of the circuitelement 50 of the second wire member 42 (a surface, of the circuitelement 50, not facing the second wire member 42), and an upper surfaceof the lower plate portion 52 b is in a close contact with a lowersurface of the circuit element 50 of the first wire member 41 (refer toFIG. 3). Further, the pressing member 54 is arranged such that thesecond wire member 42 is sandwiched from an upper side of the upperplate portion 52 a. At this time, the pin 21 b of the bottom plate 21 isinserted through a fixing hole 52 c of the heat releasing body 52 and afixing hole 54 a of the pressing member 54, and is fixed by welding etc.

For bringing the circuit element 50 in a close contact with the heatreleasing body 52, an elastic member 53 made of an elastic material suchas rubber is fixed below a lower surface of the upper plate portion 52 aof the heat releasing body 52, and below a lower surface of the pressingmember 54. The circuit element 50 of each wire member is brought intocontact by being pressed against the upper surface side of the lowerplate portion 52 b and the upper plate portion 52 a by the elasticmember 53. In other words, the circuit element 50 of the first wiremember 41 makes a close thermo conductive contact with the lower plateportion 52 b of the heat releasing body 52 by an elastic force of theelastic member 53. Moreover, the circuit element 50 of the second wiremember 42 makes a close thermo conductive contact with the upper plateportion 52 a of the heat releasing body 52 by a thrust of the pressingmember 54 and the elastic force of the elastic member 53. A shape of theheat releasing body 52 is not restricted to such shape, and may be letto be substantially L shape in a cross-sectional view, which is extendedcontinuously further upward from the upper plate portion 52 a, therebysecuring an amount of heat released.

The jetting head 3, similarly as hitherto known jetting head describedin Japanese Patent Application Laid-open No. 2005-322850, has a cavityportion 31 on a lower surface of which the nozzles 7 are formed, and onan upper surface of which pressure chambers 35 are formed, an actuator32 of a plate type, and the flexible wiring 4 as shown in FIG. 4. Thecavity portion 31, the actuator 32, and the flexible wiring 4 arestacked (are in stacked form).

The cavity portion 31 has a stacked plurality of thin plates, includinga nozzle plate arranged at a lowermost surface, and a cavity platearranged at an uppermost surface. The plurality of nozzles 7 is formedin the nozzle plate, and a plurality of pressure chambers 35communicating with the nozzles are formed in the cavity plate. At aninterior of the cavity portion 31, an ink supply channel (passage)ranging from a manifold 34, distributed over the pressure chambers 35,and reaching the nozzle 7 is formed. Due to the ink supply channel, theink introduced from the ink storage portion 22 into the ink intake port31 a of the cavity portion 31 fills the manifold 34 and the pressurechambers 35, and reaches up to the nozzles 7. The nozzles 7 and thepressure chambers 35 communicating with the nozzles 7 form a pluralityof nozzle rows and a plurality of pressure chamber rows extended in an Xdirection in a plan view, respectively. These nozzle rows (pressurechamber rows), for each ink color, are arranged in a Y direction.

As shown in FIG. 4, the actuator 32 is a plate-shaped member having asize sufficient to cover all the pressure chambers 35. The actuator 32has a plurality of plate-shaped ceramics layers 36 which are stacked,and a plurality of electrodes arranged between the ceramics layers 36.

The electrodes include individual electrodes 37 which is formedcorresponding to the pressure chambers 35, and common electrodes 38 eachof which is formed spreading over the plurality of pressure chambers 35.The individual electrodes 37 and the common electrodes 38 are arrangedalternately between the ceramics layers 36. A plurality of surfaceindividual electrodes 37 a and surface common electrodes 38 a are formedon an uppermost surface of the actuator 32 as shown in FIG. 5. Thesurface individual electrodes 37 a and the surface common electrodes 38a correspond to the plurality of individual electrodes 37 and commonelectrodes 38. The surface individual electrodes 37 a (the surfacecommon electrodes 38 a) are electrically connected to the correspondingindividual electrodes 37 (common electrodes 38) via through holes.

The surface individual electrodes 37 a and the surface common electrodes38 a are formed of an Ag—Pd metallic material. Each of the surfaceindividual electrodes 37 a has an elongated shape corresponding to ashape of the pressure chambers 35 and the individual electrodes 37, andthe surface individual electrodes correspond to pressure chambers 35(nozzles 7). Similarly as the individual electrodes 37 and the pressurechambers 35, the surface individual electrodes 37 a form a row in the Xdirection, and these electrode rows are arranged in the Y direction foreach color. Moreover, the surface common electrodes 38 a are provided inthe form of a strip and are arranged on both end portions in the Xdirection of the actuator 32. Each of the surface individual electrodes37 a and the surface common electrodes 38 a has a connecting terminal 39connecting to the flexible wiring 4. As it will be described later, eachof the connecting terminals 39 is connected to an output electrode 44 ofthe flexible wiring 4, via an electroconductive brazing filler materialsuch as solder. The connecting terminal 39 on the surface individualelectrode 37 a is formed alternately at both end portions in the Ydirection of each surface individual electrode 37 a. In other words, asshown in FIG. 5, the connecting terminals 39 are arranged in a row in azigzag (staggered) form in the X direction.

In the actuator 32 provided with the electrodes in such manner, a drivevoltage from the circuit element 50 which will be described later isselectively applied between one of the individual electrodes 37 and oneof the common electrodes 38, via the flexible wiring 4. A portion of theceramics layer 36 sandwiched between the individual electrode 37 and thecommon electrode 38 serves as a drive portion (active portion) and isdeformed by applying the drive voltage. With the deformation of thedrive portion, a pressure is applied to the ink inside the pressurechamber 35, and the ink is jetted from the nozzle 7.

Next, the flexible wiring 4 (the first wire member 41 and the secondwire member 42) of the first embodiment will be described below.

The first wire member 41 and the second wire member 42 have a substrate55 in the form of a strip made of a material such as polyimide having aflexibility and an electrically insulating property, a plurality ofelectroconductive wires 56 formed on one surface of the substrate 55,and a covering material 57 made of solder resist which covers andinsulates the electroconductive wires 56. The substrate 55, theelectroconductive wires 56, and the covering material 57 are stacked(stacked structure). The auxiliary wire 51, similarly, has a substrate,electroconductive wires, and a covering material, and the substrate, theelectroconductive wires, and the covering material are stacked.Moreover, each of the first wire member 41 and the second wire member 42has the circuit element 50 which drives the actuator 32 mounted thereon(refer to FIG. 3). An input electroconductive wire 56 a connected fromthe auxiliary wire 51 is connected to an output electroconductive wire56 b for connecting to the actuator 32, via the circuit element 50. Theoutput electrodes 44 (44 a and 44 b) to be connected to the connectingterminal 39 of the actuator 32 are formed by exposing partially theoutput electroconductive electrodes 56 b. The circuit element 50converts a driving signal transmitted in series from the circuit board23, to a parallel signal corresponding to the plurality of individualelectrodes 37, and is output to the actuator 32 through the outputelectrodes 44 of the first wire member 41 and the second wire member 42,as a voltage signal suitable for driving of the ceramics layer 36.

In the first embodiment, as shown in FIG. 6, both the first wire member41 and the second wire member 42, are stacked with the covering material57 directed toward the actuator 32. A portion of the electroconductivewires 56 is exposed toward the actuator 32 by partially removing thecovering material 57. Bumps 44 a and 44 b are formed at sites (portions)at which the electroconductive wire 56 is exposed. The circuit element50 is also connected electrically to an electroconductive wire(electrode) in which the covering material 57 is partially removed toexpose the wires toward the actuator 32.

As shown in FIGS. 3, 5, and 6, the first wire member 41 and the secondwire member 42 are stacked such that the second wire member 42 isoverlapped on an upper surface of the first wire member 41. One end ofeach of the first wire member 41 and the second wire member 42 is joined(connected) to the actuator 32, and the other end thereof is drawn inthe same direction from the actuator 32. The first wire member 41 andthe second wire member 42 are drawn to be inserted to the slit hole 25formed in the bottom plate 21 of the head holder 20, the first andsecond wiring members being drawn in a direction from a lower surface toan upper surface of the bottom plate 21, and are further drawn inparallel to the upper surface of the bottom plate 21 toward the sidewall 20 a, and are drawn to extend upward along the side wall 20 a. Thecircuit element 50 described above is mounted on a lower surface of anarea parallel to the bottom plate 21, of the first wire member 41 andthe second wire member 42.

Both the output electrodes 44 of the first wire member 41 and the secondwire member 42 of the flexible wiring 4 correspond to the plurality ofconnecting terminals 39 of the actuator 32, and are formed at positionsoverlapping with the connecting terminals 39 in a plan view. As shown inFIG. 6 and FIG. 7, the output electrodes 44 are formed to be distributedfor each of the first wire member 41 and the second wire member 42, andeach of the output electrodes 44 is provided with a bump in the form ofa protrusion (projection) made of an electroconductive brazing fillermaterial (solder) for connecting to the connecting terminal 39.

As shown in FIGS. 6 and 7, first bumps 44 a of the output electrodes 44of the first wire member 41 arranged on a lower side of the flexiblewiring 4 are arranged to face the connecting terminals 39 of theactuator 32, and first bumps 44 a are directly connected to a part ofthe connecting terminals 39. Second bumps 44 b of the output electrodes44 of the second wire member 42 overlapping on the first wire member 41,are connected to the remaining connecting terminals 39 of the actuator32, via through holes 43 which are formed in the first wire member 41.In this manner, a part of the connecting terminals 39 are connected tothe first bumps 44 a of the first wire member 41, and the remainingconnecting terminals 39 are connected to the second bumps 44 b of thesecond wire member 42. Here, the connecting terminals 39 connected tothe first bumps 44 a and the connecting terminals 39 connected to thesecond bump 44 bs are arranged to be distributed mutually in a planview.

The through holes 43 of the first wire member 41 are in areas notoverlapping with the first bumps 44 a and the electroconductive wires56, and in areas in which the covering material 57 is stacked directlyon the substrate 55, at positions facing the second bumps 44 b of thesecond wire member 42. The through holes 43 are holes each of which isdrilled continuously through the substrate 55 and the covering material57, and is formed by a machining such as punching. A process for formingsuch through holes 43 is easier and needs less cost as compared to aprocess of partially removing the covering material 57 for forming theoutput electrode 44 as described above.

As shown in FIG. 6, a height L2 of the second bumps 44 b of the secondwire member 42 is more than a height L1 of the first bumps 44 a of thefirst wire member 41. Here, the height L2 of the second bumps 44 b isadjusted such that, each of the second bumps 44 b protrudes from one ofthe through holes 43 of the first wire member 41 when the second wiremember 42 is overlapped on the first wire member 41. The height isadjusted such that, when an amount of projection of the first bumps 44 aeach of which is projected (protruded) from the surface of the firstwire member 41 toward the actuator 32 is let to be L3, an amount ofprojection of the second bumps 44 b projected (protruded) from thesurface through the through holes 43 is also L3. In other words, anadjustment is made such that, the amount of projection of the firstbumps 44 a and the second bumps 44 b from the surface toward theactuator 32 in the first wire member 41 becomes the same. Therefore, afront end of the first bumps 44 a and a front end of the second bumps 44b are in the same plane. In this case, at the time of electricallyconnecting the output electrodes 44 to the surface electrodes 39 of theactuator 32, it is possible to make an amount of the brazing fillermaterial between the connecting terminals 39 and the output electrodes44 to be almost the same, and to make uniform a pressure to be exertedat the time of joining. Therefore it is possible to suppress variation(unevenness) in connections, and to reduce an occurrence of a connectiondefect.

In this manner, the first bumps 44 a and the second bumps 44 b to beconnected to the actuator 32 are provided separately for the first wiremember 41 and the second wire member 42. Therefore, even when a wiringpitch of each of the single wire members, namely the first wire member41 and the second wire member 42, is rough, it is possible to makehighly dense the wiring pitch as a whole by stacking the first andsecond wire members 41, 42 (refer to FIG. 7). As it has been describedabove, making the wiring pitch highly dense by forming wires on bothsurfaces of a single wire member may be taken into consideration.However, according to verifications (tests) of inventors of the presentinvention, in the flexible wiring 4 of the first embodiment, it ispossible to realize a highly dense wiring pitch (highly dense wiring)than in a case of double-sided wiring of the single wire member. Even inthe case of the double-sided wiring, all the electrodes are to be formedon one side. Therefore, through holes, which expose the wires formed onthe other surface, are to be formed, avoiding positions of the wires andthe electrodes on the one surface. In this case, there are limitationsin carrying out such machining on one wire member. On the other hand, asin the flexible wiring 4 of the first embodiment, by arranging aplurality of wire members with single-sided wiring and combining thesewire members, it is possible to realize the highly dense wiring. In FIG.7, an embodiment, in which a wiring pattern of the first wire member 41and a wiring pattern of the second wire member 42 do not overlap, isshown. However, unless positions of the first bumps 44 a do not overlapwith those of the second bumps 44 b, a portion excluding an area nearthe output electrode 44 in the electroconductive wire 56 may overlap ina vertical direction.

In the recording apparatus 1 of this embodiment (the first embodiment),the nozzles 7 are arranged in four nozzle rows 7 a, 7 b, 7 c, and 7 d(hereinafter, nozzle rows 7 a to 7 d) (nozzle groups). Here, the nozzlerows 7 a, 7 b, 7 c, and 7 d jet the black ink, the cyan ink, the magentaink, and the yellow ink respectively. The drive portions of the actuator32 are provided corresponding to the nozzles 7, respectively. In otherwords, there is n number of drive portions corresponding to the n numberof nozzles 7 in each of the nozzle rows. Moreover, a driving signalthrough the circuit element 50 of the first wire member 41 is input to apart of the n number of drive portions, and a driving signal through thecircuit element 50 of the second wire member 42 is input to theremaining drive portions. For description, in FIG. 8, the nozzles 7through which the ink is jetted by the driving signal via the circuitelement 50 of the first wire member 41 are shown by white circles, andthe nozzles 7 through which the ink is jetted by the driving signal viathe circuit element 50 of the second wire member 42 are shown by blackcircles. FIG. 8 is merely an example of an arrangement of nozzles, andthe white circles and the black circles are not necessarily required tobe arranged alternately.

In the recording apparatus 1 of the first embodiment, two circuitelements 50 are used, and there is a variation in characteristics of thetwo circuit elements 50. When the driving signal via one of the circuitelements 50 is let to correspond to nozzle rows 7 a and 7 b, and thedriving signal via the other of the circuit elements 50 is let tocorrespond to nozzle rows 7 c and 7 d, the variation in characteristicsof the two circuit elements leads to a variation in jettingcharacteristics of the nozzle rows 7 a and 7 b, and jettingcharacteristics of the nozzle rows 7 c and 7 d. Therefore, as it hasalready been mentioned earlier, by distributing a signal via one of thecircuit elements 50 to a plurality of nozzle rows, it is possible toreduce substantially an effect of the variation in characteristics ofthe circuit elements.

Next, the flexible wiring 4 of a second embodiment will be describedwith reference to FIGS. 9 and 10. Same reference numerals are used forcomponents having the same structure as in the first embodiment, anddescription of such components is omitted. In the second embodiment, asshown in FIG. 10, the second wire member 42 is arranged such that thesubstrate 55 is facing the first wire member 41, and the outputelectrodes 44 are formed by providing the second bumps 44 b at positionsof the electroconductive wires 56 which are exposed by the substrate 55being removed partially. Similarly as in the first embodiment, thesecond bumps 44 b are protruded toward the actuator 32, via the throughholes 43 penetrated in the first wire member 41.

Since each of the circuit elements 50 is mounted on the coveringmaterial 57 of the first wire member 41 and the second wire member 42,the circuit elements 50 are mounted on surface not facing mutually, ofthe first wire member 41 and the second wire member 42. The heatreleasing body (heat sink) 52 having a U-shape is arranged on the uppersurface of the bottom plate 21, and as shown in FIG. 9, an upper surfaceof the circuit element 50 of the first wire member 41 is in a closecontact with a lower surface of the upper plate portion 52 a of the heatreleasing body 52, and a lower surface of the circuit element 50 of thesecond wire member 42 is in a close contact with an upper surface of thelower plate portion 52 b of the heat releasing body 52. The elasticmember 53 made of rubber is inserted to be compressed between the uppersurface of the first wire member 41 and the lower surface of the secondwire member 42, at a position overlapping with the circuit element 50.Each circuit element 50 makes a close contact with the heat releasingbody 52 due to an elastic force (restoration force) of the elasticmember 53.

Unless it is possible to project the first bumps 44 a of the first wiremember 41 directly toward the actuator 32, and to project the secondbumps of the second wire member 42 toward the actuator 32 via thethrough holes 43 in the first wire member 41, any of a front surface anda rear surface of the first wire member 41 may be overlapped with thesecond wire member 42, and appropriate modifications which fairly fallwithin the basic teachings are possible without restricting to the firstembodiment and the second embodiment.

In the embodiments described above, the flexible wire has two wiremembers each having wirings on one side (one surface) thereof.Therefore, as it has been described above, it is possible to realizehighly dense wiring as compared to a case of using one wire member witha double-sided wiring. Moreover, at the time of forming through holes inone of the wire members, at positions corresponding to the electrodesprovided on the other of the wire members, even when there is someposition shift, it is possible to form the holes once again, providedthat the through holes do not coincide with wires formed on the one ofthe wire members. Whereas, when the wires are formed on both surfaces,it is necessary to position the wire members to form the through holessuch that the wires on the one surface is exposed through the throughholes to the other surface. Therefore, a control of positioning of thethrough holes becomes necessary, and a manufacturing of the wire membersbecomes difficult. Moreover, in the flexible wiring according to thepresent invention, it is possible to make flat a surface on which thebumps are not formed. For example, with the flat surface facingdownward, at the time of arranging a device such as an IC chip etc. on asurface at the opposite side thereof, it is possible to position thedevice easily and assuredly without having an effect of unevenness dueto the bumps etc.

In the embodiments described above, the flexible wiring 4 has beenformed by two wire members. However, the flexible wiring 4 may be formedby three or more wire members. Moreover, a plurality of wire members isnot necessarily required to be drawn from the actuator 32 in a samedirection, and may be drawn in different directions.

Furthermore, the flexible wiring 4 of the present invention may beconnected not only to the actuator 32 of the liquid droplet jettingapparatus, but also to other device. It is particularly suitable in acase where a particularly highly dense wiring is necessary. For example,any arbitrary device (electronic circuit) including various sensordevices such as an IC chip and a CCD may be connected as a device. As itis shown in FIG. 11, it is possible to form bumps of different heightson a side of a device such as an actuator 132. In the embodimentsdescribed above, the bumps 44 a and 44 b having different height havebeen formed on each of the wire members of the flexible wiring 4.However, in an example shown in FIG. 11, bumps 144 a and 144 b ofdifferent height are formed on terminals of the actuator 132, and theactuator 132 is connected to a flexible wire 104 by the bumps 144 a and144 b. The flexible wire 104 has two wire members 141 and 142, and has astructure same as the flexible wiring 4 described above except that itdoes not have bumps. A difference in the height of the bumps 144 a andthe height of the bumps 144 b is about the same as a thickness of thewire member 141, and similarly as in the embodiments described above, itis possible to join the flexible wire and the actuator assuredly. Such adevice having the bumps of different heights is not restricted to anactuator of a liquid droplet jetting apparatus, and may be any arbitrarydevice (electronic circuit) including various sensor devices such as anIC chip and a CCD for example.

Next, a method of connecting an actuator and a device by using aflexible wiring as described above will be described below withreference to a flowchart shown in FIGS. 12, and 13A to 13G. Firstly, twowire members 241 and 242 each having wires formed on one surface arearranged (step S1, FIG. 13A). The wire member 241 (242), similarly asthe wire member 41 (42) of the embodiments described above, has asubstrate 255, electroconductive wires 256 a (256 b) arranged on onesurface of the substrate 255, and a covering material 257 which coversthe electroconductive wires 256 a (256 b). The electroconductive wires256 a are exposed by removing a portion (a part) of the coveringmaterial 257 of the wire member 241, and electrodes 260 a are formed(step S2, FIG. 13B). Similarly, the electroconductive wires 256 b areexposed by removing a portion of the covering material 257, andelectrodes 260 b are formed (step S3, FIG. 13C). Next, when the wiremember 241 and the wire member 242 are positioned, through holes 243 areformed in the wire member 241, at positions overlapping with theelectrodes 260 b (step S4, FIG. 13D). Further, the wire members 241 and242 are positioned and stacked such that the through holes 243 overlapwith the electrodes 260 b (step S5, FIG. 13E). Next, bumps 244 a and 244b each having different height, are formed in the electrodes 260 a and260 b respectively (step S6, FIG. 13F). Here, the bumps 244 a and 244 bare formed by an electroconductive brazing filler material. A differencebetween the height of the bumps 244 b and the height of the bumps 244 ais adjusted to be about the same as a thickness of the wire member 241.In other words, an adjustment is carried out such that, front ends ofthe bumps 244 a and 244 b are at the same height. Finally, the bumps 244a and 244 b are connected to terminals of the actuator 232 (step S7,FIG. 13G).

In this manner, it is possible to connect the flexible wire having thetwo wire members 241 and 242 to a device such as an actuator. In theabovementioned description, it is not necessary to carry out the processin an order of steps from S2 to S7, and the order of the process may bechanged according to the requirement. For example, while the wiremembers 241 and 242 are positioned and stacked, the through holes 243may be formed in the wire member 241, and the covering material 257 ofthe wire member 242 may be removed. In this case, it is possible to formthe through holes 243 and to form the electrodes 260 b exposed throughthe through holes 243 simultaneously. Moreover, the electrodes 260 a and260 b may be formed on the wire members 241 and 242, and further, withthe bumps 244 a and 244 b having different lengths formed on theelectrodes 260 a and 260 b, the wire members 241 and 242 may bepositioned and stacked.

The bumps 244 a and 244 b may not be necessarily formed on the wiremembers 241 a and 241 b, and as it has been described above, two type ofbumps having different height may be formed on terminals of the actuator232, and the two stacked wire members 241 and 242 and the actuator 232may be connected by the bumps. Moreover, the electrodes 260 a and 260 bmay be formed by removing portions of the substrate 255. Moreover, thedevice to be connected to the wire members is not restricted to be anactuator, and any arbitrary device may be used.

What is claimed is:
 1. A liquid droplet jetting head which jets dropletsof different types of liquids, comprising: a flexible wiring memberwhich is arranged to face a device, and which connects the device and anexternal signal source, the flexible wiring member comprising: two wiremembers which are stacked mutually, and each of which have a belt-shapedsubstrate, a plurality of wires formed on one surface of the substrate,a plurality of electrodes connected to the wires respectively, and aplurality of bumps each projected from one of the electrodes toward thedevice, wherein a plurality of through holes is formed in one of thewire members stacked on a side of the device, and the bumps of the otherof the wire members face the device through the through holes formed inthe one of the wire members, wherein the one of the wire memberscomprises a facing surface facing the device and exposed to an exteriorof the flexible wiring member, wherein the bumps of the other of thewire members facing the device via the one of the wire members areformed to be projected, from the facing surface of the one of the wiremembers facing the device through the through holes formed in the one ofthe wire members; and a height of the bumps of each of the two wiremembers is adjusted such that a projection amount of a portion of thebumps projected through the through holes projecting from the facingsurface of the one of the wire members is the same as a projectionamount, of a portion of the bumps provided on the one of the wiremembers projecting from the facing surface of the one of the wiremembers; a cavity section which is filled with the liquid, and in whicha plurality of nozzle groups corresponding to the types of the liquidsrespectively are formed, each of the nozzle groups having a plurality ofnozzles; and an actuator serving as the device and including a pluralityof driving sections which correspond to the nozzles respectively andwhich apply selectively a jetting pressure to the liquids, respectively,in the cavity section, wherein a circuit element is mounted on thesubstrate of each of the wire members of the flexible wiring member, anda signal from the external signal source is divided into a plurality ofdriving signals each traveling through one of the wire members and eachof the driving signals is inputted to the driving sections via one ofthe circuit elements; and a part of the driving signals traveled throughthe circuit element of each of the two wire members is distributed andinputted to a part, of the driving sections, corresponding to thenozzles in different nozzle groups.